Passing function names from forms into J

I’m trying to call on a function, the name of which is being passed into the JavaScript as a variable from a form. Unfortunately, JavaScript isn’t recognizing the passed variable as a method.

I’ve presented the problem on two Web pages, a form page and a personalized message page. Only the age range radio buttons present this problem. Here’s the URL for the first of the two pages: http:/www.geocities.com/eightypoundpack/submit-congrat2.html

Thanks in advance for any help you can give me.